Differential Diagnosis for Red and Itchy Rash

The patient presents with a red and itchy rash that comes and goes, with no changes in soap or detergent. Here's a differential diagnosis organized into categories:

• Single Most Likely Diagnosis
  • Atopic Dermatitis (Eczema): This is a common condition in children, characterized by itchy, red, and scaly skin. The intermittent nature of the rash and the absence of changes in soap or detergent make this a likely diagnosis.
• Other Likely Diagnoses
  • Contact Dermatitis: Although the mother denies any changes in soap or detergent, it's possible that the patient has come into contact with another allergen or irritant that's causing the rash.
  • Allergic Reaction: An allergic reaction to a food, insect bite, or other substance could cause a red and itchy rash.
  • Seborrheic Dermatitis: This condition causes a red, itchy rash on the scalp, face, and other areas of the body.
• Do Not Miss Diagnoses
  • Bullous Pemphigoid: A rare autoimmune disorder that causes blistering of the skin, which can be life-threatening if left untreated.
  • Stevens-Johnson Syndrome: A severe skin and mucous membrane disorder that can be life-threatening if not promptly treated.
  • Kawasaki Disease: A rare condition that causes inflammation in the blood vessels, which can lead to serious complications if not treated promptly.
• Rare Diagnoses
  • Pityriasis Rubra Pilaris: A rare skin disorder that causes constant itching and scaling of the skin.
  • Cutaneous T-Cell Lymphoma: A rare type of cancer that affects the skin and can cause a red and itchy rash.
  • Erythema Multiforme: A rare skin condition that causes a target-shaped rash and can be associated with infections or medications.